Termination of semiconductor components

ABSTRACT

A Semiconductor component, such as an IGBT, a thyristor, a GTO or a diode, and especially a Schottky diode is provided that is capable of blocking for producing a termination portion of a semiconductor component. An insulator profile of an insulator portion includes a curved surface, which is free of steps and is produced by gray-tone lithography in the termination portion of an anode. The device also includes a substrate that is covered with an insulating layer having a thickness of between 0.5 μm and 15 μm, an insulator layer having a thickness is covered with a photosensitive layer (photoresist layer) where the photoresist layer is exposed through a mask, which changes in its gray-tone value in accordance with the course of curvature of the surface of at least one insulator profile, and is subsequently structured to form at least one resist remainder. The structured photoresist layer and the insulator layer are substantially planely removed by a dry-etching process, in order to transfer the at least one resist remainder—defined by the structuring—by shape into the insulator and to form at least one insulator profile around the anode.

[0001] In semiconductor components having at least one blocking p-njunction, the latter appears on the surface of the substrate, on whichand in which the semiconductor component is realized, somewhere betweenthe live contacts. In said surfacing areas high electric fieldstrengths, in case the p-n junction is blocking, i.e. a higher voltageis applied to the cathode than to the anode or a controllablesemiconductor device is not yet connected through its gate terminal,result in undesired leaking currents flowing between the anode and thecathode, which currents are designated as positive or negative reversebias current depending on the direction of polarization of the voltageto be blocked or reversed. For reducing that portion of the reverse biascurrents, which is caused by high field strengths in the terminationportion, so-called “junction terminations” are employed in the priorart, which, for example in the form of specially formed field plates,cause an optimized course of equipotential lines and thus avoid hightfield strengths in the termination portion of such components, cf. DE-A195 35 332 (Siemens), column 3, line 58 to column 4, line 35; or“Muitistep Field Plates . . . ”, IEEE Transactions on electron. devices,Vol. 39, No. 6, June 1992, from page 1514 onwards; “The Contour of anOptimal Field Plate”, IEEE Transactions on electron. devices, Vol. 35,No. 5, May 1988, from page 684 onwards; and finally “TheoreticalInvestigation of Planar Junction Termination”, Solid-State Electronics,Vol. 39, No. 3, pages 323 to 328, 1996. The planar junction terminationsdescribed therein are optimized with regard to their geometry, on theone hand as a field plate having steps and on the other hand as anoptimized steadily curved field plate having a modified ellipticalgeometry. However, the prior art has not yet succeeded in economicallyfabricating the optimized geometric structure of a field plate in thetermination portion of a semiconductor component capable of blocking,especially of such a component to which a high voltage of more than 500V can be applied.

[0002] It is the object of the invention to fabricate the aforementionedsemiconductor components, which are in particular highly blocking orcapable of blocking, on an economic basis, i.e. at low costs, andnevertheless utilize their maximum blocking capacity.

[0003] This is achieved by the invention, if a termination portion ofthe inner anode metallic coating comprises an insulator profile, havinga shape which begins flat and is curved outwards and upwards in asteadily increasing manner, which portion is the “curved portion” of theinsulator profile, and having a “base portion”, which is locateddirectly adjacent thereto and is virtually planar, said base portiontogether with the curved portion determining the cross-section of theinsulator profile.

[0004] The insulator profile is designed such that, between the curvedinner metallic coating, outwardly extending the anode, and the outermetallic coating, located outwards of and adjacent to the base portionof the insulator profile, which will in most cases be the cathode, peakvalues of an electric field generated during operation can be avoided.The insulator profile is produced by a method, in which an at firstdeposited insulator layer having a thickness is additionally coveredwith a resist layer over the entire substrate, which resist layer isilluminated through a mask in a structured manner, which mask changes inits gray-tone value in accordance with the desired course of curvaturein the curved portion of the respective insulator profile. The gray-tonevalue in the mask is transferred into the resist layer by exposure,which layer can be structured subsequent thereto, especially bydeveloping, in order to then transfer the structure of the developedresist layer into the insulator layer having a thickness by an etchingprocess, such as RIE (reactive ion etching), wherein it is an advantageif the etching rate of the insulator layer and the etching rate of theresist remainders, remaining after developing the exposed resist layer,are about equal in order to prevent a not-to-shape transfer of theresist profile into the insulator.

[0005] The resulting insulator profiles can either surround the anode inthe form of a wall or a plurality of insulator profiles may be providedwhich are arranged in an outwards staggered manner and the curvedsurface of which is differently shaped. If a plurality of staggeredinsulator profiles is provided (claim 2, claim 3), the curvature of thesurfaces of the curved portions is not equal, but steadily increaseswith each profile being located further outwards (claim 3).

[0006] On the mentioned respective curved surfaces metallic coatings aredeposited, which, for the insulator profile outwardly adjoining theinner anode, conductingly pass over into the anode metallic coating.

[0007] The structuring, which is coded in its gray-tone value, isperformed, during exposure, such that a desired light-intensity profileis coded into the mask by the semitone process, i.e. via a pixel screen,and that the pixel sizes are transferred below the resolving limit of areducing projection exposure in an almost continuous course of exposureof the resist layer, by which it is thus possible to produce continuoussurfaces curving outwards and upwards; the insulator profiles formedaccording to the invention thus have at least one continuous surface(without steps) steadily extending across a substantial area, whichsurface is designed in a manner which theoretical calculations for anoptimized course of flux lines, when a reverse bias voltage load orconducting-state blocking load is applied, imply to be favorable.

[0008] By use of the invention the thickness of the insulator layer canbe continuously varied in a process in a predetermined and controlledmanner over a wide area of up to 10 μm; it is not necessarily requiredto give the surface curvature an ideal course as long as it is ensuredthat the substantial increases of field strength can be avoided and thatthe reverse bias voltage load at the termination of the anode towardsthe cathode does not include substantial peak values.

[0009] Even with semiconductor components having reverse bias voltagesof more than approx. 500 V, the theoretically maximally possible reversebias voltage can almost be achieved at minimum space requirements forthe junction termination, i.e. the “blocking capacity” of the occupiedspace can be fully utilized. The minimum space requirements areimportant in said components, a plurality of which is produced from onewafer, and wherein utilizing the blocking capacity to a maximallypossible extent becomes the more important the higher the reverse biasvoltages are. Said aspects are of particularly great importance forhighly blocking IGBTs.

[0010] Even with Schottky diodes, which are not based on a p-n junction,but which utilize the blocking capacity of a metal-semiconductorjunction, the insulator profiles produced according to the invention maybe employed in an advantageous manner. At the edge of themetal-semiconductor junction the small effective radii of curvaturewould result in excessive field increases. For preventing saidincreases, diffused guard rings are employed in the prior which,however, at strong conducting-state loads, cause an undesired injectionof minority charge carriers. By use of the insulator profiles and fieldplates produced according to the invention such an injection of chargecarriers does not occur and the diffusion process during production canbe omitted.

[0011] The use of the invention, which is limited to measures performedat the surface of the semiconductors, is particularly advantageous evenif the power semiconductors are to be improved on the basis of siliconcarbide (SiC), as an example for a semiconductor having a high bandwidth (claim 12). In said semiconductors a very low diffusion constantfor doting substances must be put up with and this being the reason whytermination portions can virtually not be produced by diffusion.

[0012] The component, with the insulator profiles produced according tothe invention, comprises profiles which, at the transition to the anode,do not terminate in a continuous or steady manner, but terminate with asmall step in the order of magnitude of more than 5 nm and less than 50nm. Said step being very small compared to the thickness of the metalliccoating and is virtually of no consequence, but results from the methodof production by gray-tone lithography. Thus, the metallic coating may,for example, have a thickness of approx. 1 μm, while the “step” of theinsulator at the end of the curved portion of the insulator 20 producedby gray-tone lithography is 20 nm.

[0013] Gray-tone lithography works in such a manner that the substrateis covered with an insulator layer, which is at first covered with aphotosensitive layer, which is exposed in such a manner that the courseof curvature of the surface of the insulator profile is exposed into thephotoresist layer by gray-tone variation, i.e. by adapting thelight-intensity distribution to the shape of the insulator profile,which photoresist layer is structured subsequent thereto by developing(claim 11). The photoresist layer structured in such a manner nowconsists of resist remainders only, forming blocks on the insulatorlayer, which blocks correspond to the insulator profiles. By means of anetching technique, for example a dry-etching process, the resistremainder still present on the substrate surface is conformally etchedinto the insulator layer, wherein the insulator layer is substantiallyplanely removed and is more extensively removed where there are noresist remainders (claim 6).

[0014] The transfer by shape is promoted if the etching rates of theresist remainders and the insulator layer are equal; if they are notequal the shape of the resist remainder must be adapted accordingly,which may be effected by adaptingthe intensity distribution duringexposure.

[0015] The height of the insulator profile in the base portion can beselected to be higher or lower (claim 4, claim 5). If the insulatorprofile has a height of more than approx. 5 μm in the base portion, theslope at the end of the curved portion at the transition to the baseportion is more than 100. The curved portion ends steeper here than inthe insulator profile, which is flat in the base portion (claim 5). In ahigher base portion the normal extension of the base portion issubstantially ten times the height of the base portion, preferably evenmore.

[0016] If a more flat base profile, which is easier to fabricate bygray-tone lithography, is selected (claim 5), an additional screenelectrode, which is located above the anode potential of the innermetallic coating, can be formed above the junction termination. Thelateral extension of the base portion is a multiple of the height of thebase portion here, in particular more than 50 times to 200 times theheight of the base portion, which especially has a height of 2 μm.Between the end of the curved portion and the beginning of the upwardcurvature of the additional screen electrode (hood) there is anintermediate region, which, in its extension, is adapted substantiallyto the radius of curvature of the curved lateral outer end of the hood,in which intermediate region the distance between the hood, whichfollows a substantially horizontal path here, and the surface of thebase portion is substantially constant.

[0017] The curved portion of the hood is preferably a quarter circle(claim 7). Its curvature can be considerably more pronounced than thatof the surface of the curved portion within the base portion of theinsulator profile.

[0018] The region between the anode metallic coating and the outercathode metallic coating, i.e. the region of one or more staggeredinsulator profiles, can be covered in an elevated manner with awall-like casting compound, in order to prevent flashover (claim 9).

[0019] If insulator profiles arranged in an outwards staggered mannerare provided (claims 2, 3), below each of the staggered metalliccoatings, extending beginning from the outer end of the base portion ofthe insulator profile located further inwards up to the upper end of thecurved portion of the base profile located further outwards, astrip-shaped compensating area can be provided in the substrate, whichis diffused into the substrate and which transfers the potential presentat the respective location when a voltage is applied from the substratearea to the respective metallic coating (claim 10). The doting of saidstrip-shaped zones diffused into the substrate substantially correspondsto the doting which is selected for a p+ region below the anode metalliccoating.

[0020] The penetration depth of the diffused zones below the metalliccoating is preferably only low, preferably less than 10 μm, whichtechnologically does not give rise to field peaks. The p+ diffusionzones transfer their potential to the respective metallic coatingcurving outwards and upwards (away from the substrate).

[0021] The lateral extension of the metallic curved portions should beadjusted to the space-charge depth and at the same time correspond totwice to three times the space-charge depth.

[0022] The invention(s) are described and completed in the following bymeans of a number of embodiments.

[0023]FIG. 1 shows, in section, a cutout of an active part of asemiconductor component capable of blocking, here a diode having ananode 1 and a cathode 2, 3 as well as a termination portion of theanode, which, by a planar junction termination, here a field plate, isformed such as is shown in FIG. 3, which each show enlargements of theregion AV.

[0024]FIG. 2a is an illustration of the structuring of a photoresistlayer 20, which is at first present over the entire surface and which,after structuring (by exposure), is conformally transferred into theinsulator 10 having the illustrated shape 20 a, by the shown dry etchingprocess 60, here a reactive ion etching (RIE) process.

[0025]FIG. 2b is, corresponding to FIG. 2a, an illustration of staggeredresist profiles 20 b, 20 c, 20 d, which are arranged outwards in serieson the insulator 10, wherein it is just begun, by reactive ion etching60, to conformally transfer the resist remainders (resist profiles),already having the shape of desired insulator profiles, into theinsulator layer 10.

[0026]FIG. 3a is a section through a finished junction termination,produced after completion of the reactive ion etching 60 according toFIG. 2a and which, by a metallic coating 30 a, extends the anodemetallic coating 1 in the curved portion KB of the insulator profile 10a. The insulator profile 10 a has a width corresponding to approx. 10times to 15 times the height h₁₀. For example, a selected height of 10μm results in a lateral extension of the profile of 100 μm, which is,however, highly dependent on the desired reverse bias voltage.

[0027]FIG. 3b is a result of the completed method of production for thestaggered insulator profiles, which were begun to be transferred intothe insulator layer 10 in FIG. 2b. For example, three outwards staggeredinsulator profiles 10 b, 10 c, 10 d are produced, the curvatures ofwhich are steeper towards the outside. Also in this case the figure isonly a schematic illustration, wherein the intersection lines “S” removea large region of unchanged shape.

[0028]FIG. 4 and

[0029]FIG. 4a are illustrations of a more flat insulator profile 11,which, at the inner end towards the anode 31, has a small step 11 shaving a height “d”, which is shown more clearly in the enlargedillustration of FIG. 4a. Said step has a height of less than 50 nm,which height is preferably in an order of magnitude of between 20 nm and30 nm, with a metallic coating 31, 31 a, 31 b covering it having athickness of approx. 1 μm. In FIG. 4 the flat insulator profile issupplemented by a metallic screen 32, which, starting from the anodemetallic coating 31, is formed in the manner of a hood and is curved 32a laterally outwards and upwards adjacent to the curvature of themetallic coating having an ellipse-like form. A casting compound 41insulates the region between anode, metallic hood 32 and cathode 3,outwards of the end of the insulator profile, which here has lateraldimensions of approx. 50 times to 200 times the height of the profile 11in the base portion.

[0030]FIG. 5 schematically illustrates the structure of an insulatorprofile produced by gray-tone lithography including the curved portionKB and the extensively extending base portion SB, the latter having anabout constant height “h”, whereas the curved portion steadily decreasesfrom said constant height towards the anode, where, preferably by asmall step 11 s, it reaches the level of the substrate 9. A metalliccoating MET1 is deposited in the curved portion, which coating extendsthe anode metallic coating 1, 31 and permits a controlled course of fluxlines between the anode and the external cathode MET2 free of high peakvalues.

[0031]FIG. 6 is an approx. true to scale illustration of the arrangementof FIG. 4 with the insulator profile having a flat base portion SB.

[0032] The semiconductor component capable of blocking of FIG. 1 isprovided with intersection regions S so that only cutouts of the actuallateral extension of this semiconductor component can be seen herein.Two essential regions are the anode region 1 and the junctiontermination, being provided with an insulator profile here, which willbe described in more detail with respect to FIGS. 3a and 3 b. Therelevant cutout AV is illustrated in more detail and to a larger scaletherein.

[0033] Below the anode 1, which is formed by a metallic coating, thereis a p+ region of high doting concentration, which is to be consideredvirtually as a metallic region. In the termination portion the metalliccoating 1 changes in form of an upwards curved field plate, whichcurvature is determined by the profile shape of the insulator in thecutout region AV. Outwards of the insulator profile the cathode 3 isprovided as well as on the opposite side of a substrate 9, which formsthe semiconductor component. Below the outer metallic coating 3 there isa channel stop 7, which is formed as an n+ region of high concentrationdiffused into the substrate. The cutout AV of FIG. 1 is shown enlargedin FIGS. 3a and 3 b.

[0034] In FIG. 3a the termination portion of the anode 1 with the p+region 8 arranged underneath is an upwards curved metallic coating 30 a.It is covered by a wall-like casting compound 40 extending above theinsulator profile 10 a and reaching as far as the outer metallic coating3 above the channel stop 7. Also in this case the junction terminationis arranged on the substrate 9.

[0035] The insulator profile 10 a is to be divided, for reasons ofillustration, into a curved portion KB and a base portion SB, whereinthe curved portion KB is located below the outwards and upwards curvedmetallic coating 30 a as a continuation of the anode metallic coating 1and the base portion SB is located outwards of the outer end of saidextended curved metallic coating 30 a having a substantially constantheight h₁₀.

[0036] In FIG. 3b a number of the shapes shown in FIG. 3a are arrangedin a staggered manner. Herein the insulator profile is lower in the baseportion SB than in FIG. 3a. In the illustrated example, three baseprofiles 10 b, 10 c, 10 d connected outwards and in series are providedinstead, all of which substantially following the structure of the baseshape of FIG. 3a, except for the height h₁₀. The curved portions KB ofeach of the insulator profiles 10 b, 10 c, 10 d, each being locatedinternal of and adjacent to the respective base portion SB, are eachmore curved from the inside towards the outside for each individualbase. This results in surfaces of the curved portion, on which therespective metallic coating 30 b, 30 c, 30 d is arranged, and in anoutwards staggered respectively changing profile, each profile startingapprox. horizontally and extending along the curved portion in anoutwards and upwards inclined manner. The respective angle of the endportion of the curved metallic coating is larger in the second metalliccoating 30 c than in the first metallic coating 30 b and is larger inthe third metallic coating 30 d than in the second metallic coating 30c.

[0037] Starting from the inner anode 1, the first curved metalliccoating 30 b is located directly adjacent thereto. Outwards of the firstinsulator profile 10 b, located below it, is the second curved metalliccoating 30 c, which includes a horizontal region 1′, below which a p+zone 7 b is diffused into the substrate. Said zone will transfer thepotential present at the component at the respective location when avoltage is applied from the substrate area 9 to the metallic coating 1′so that outwards staggered potentials will be defined, which aresuspected by the metallic coatings and result in a field strength marchin the curved portion, which largely avoids peak values. Accordingly,also the horizontal orientation of the metallic coating 1″ locatedfurther outwards is provided horizontally above a further p+ zone 7 a,being diffused into the substrate and extending towards the curvedportion 30 d, which has already been explained. Outwards of theoutermost insulator profile 10 d the cathode metallic coating 3 isprovided including a channel stop 7, as illustrated in FIG. 3a. Therespective intersection regions S cut out those regions, which have afar lateral extension and in which no change of shape is provided.

[0038] The zones 8, 7 b, 7 a, which are diffused into the substratebelow the metallic coatings of FIGS. 3a and 3 b, have a low penetrationdepth of less than 10 μm only, preferably 3 to 6 μm.

[0039] The semiconductor according to FIG. 3b is very cost-effectivewith regard to production since the insulator profiles have a low heighth₁₀ only in the base portion SB. The height h₁₀ will be less than 5 μm,preferably in the order of magnitude of 2 μm.

[0040] During operation, when a reverse bias voltage or blocking voltageis applied, the described three staggered metallic coatings, from theanode 1 over the first stage 1′ including the curved portion 30 c andover the second stage 1″ including the curved portion 30 d, havedifferent potentials, which are transferred by thepotential-transmitting zones 7 b, 7 a to the metallic coatings. Theextensions of the potential-transmitting zones 7 a, 7 b, which arediffused into the substrate to a low depth, from the crystalline regionof the substrate 9 are chosen such that each of them begins internal ofand below the outer end portion of the base portion of the insulatorprofile and extends outwards up to approx. that region, in which theinsulator profile located further outwards with its curved portion KBbegins to emerge or increase in height.

[0041] The production of the geometries according to FIGS. 3a and 3 bwill be explained with reference to FIGS. 2a and 2 b.

[0042]FIG. 2a shows the substrate 9 having an insulator layer 10 formedthereon, usually made of silicon oxide. In FIG. 2a the starting point isillustrated, at which a shape 20 a of a resist profile or resistremainder formed after structuring (by exposure) is conformallytransferred from a photoresist layer 20, present over the entire surface(illustrated by dashed lines), into the insulator layer 10 located belowit. As the etching process a dry etching process, here a reactive ionetching by ion radiation 60, is illustrated. Prior thereto an area 8 (p+diffusion area), diffused into the substrate 9 below the anode to beformed, and a channel stop 7, diffused in to the substrate and having ann+ diffusion area (outwards of the resist profile to be formed), areprovided. On the thus prepared substrate 9 an insulator 10 is uniformlyapplied, substantially having the height, which a future resist profileis to have in the base portion SB of FIG. 3a. An additional resist layer20 is deposited on the insulator profile, which layer is at firstilluminated through a mask in a structured manner, which mask changes inits gray-tone value in accordance with the respective course ofcurvature in the curved portion KB of the insulator profile. Thegray-tone value present in the mask (not shown) is transferred byexposure into the resist layer 20, which is structured subsequentthereto (especially by developing) in order to then transfer, by meansof the etching process illustrated in FIG. 2a, the resist remaindersremaining after exposure and development into the insulator layer 10,wherein, figuratively speaking, the surface of the resist layer 20present so far is lowered onto the surface of the substrate, i.e. theremaining resist relief 20 a, as the insulator profile, is (figurativelyspeaking) lowered into the insulator layer. The insulator 10 is removedin those regions where there are no resist blocks and is removed to aminor extent where the height of the resist remainder 20 a is low,whereas in those regions where the resist remainder 20 a is to form thebase portion SB little to nothing is removed from the insulator height.Thus, after the conformal projection of the resist remainder 20 into theinsulator layer 10, a shape of the insulator profile 10 a having acurved portion KB and a base portion SB is produced, as is shown in FIG.3a, however, yet without metallic coatings 1, 3. Said metallic coatingsare applied subsequent thereto, possibly also the wall-like castingcompound 40, in order to complete the junction termination.

[0043] For the conformal projection it is advantageous to substantiallyequalize the etching rate of the insulator layer 10 and the etching rateof the remaining resist remainders 20 a so that no distortions willemerge during formation of the base profile, in particular in the curvedportion KB. If a conformal projection is achieved, the angle ofinclination α₁ of the resist remainder 20 a will be projected directlyin the angle of inclination α₁ in the slope at the upper end of themetallic coating 30 a in FIG. 3a, or the surface OF of the curvedportion KB will have said slope in the laterally outer end portion,respectively.

[0044] The structure of FIG. 3b is produced in accordance with themethod of production schematically illustrated in FIG. 2b in the samemanner, which method is performed analogously to FIG. 2a. Herein, withthe same number of process steps, a staggered arrangement of insulatorprofiles 10 b, 10 c, 10 d was projected from respective resistremainders 20 b, 20 c, 20 d in accordance with the resist remainder 20 aof FIG. 2a.

[0045] Also in FIG. 2b, the starting point is the plane resist layer 20,which is illuminated in a structured manner and leaves behind resistremainders, which are conformally projected by means of a dry etchingprocess 60 into the insulator 10, which is selected thinner here, theheight of which h₁₀ being in an order of magnitude of less than 5 μm,especially 2 μm, for the staggered arrangement.

[0046] Prior to applying the insulator layer 10, as already explainedwith regard to FIG. 3b, the potential-transmitting zones or

[0047] —for a circular design—rings 7 a, 7 b are diffused into an

[0048] n⁻ substrate 9, wherein said zones are arranged in such a waysuch that they will be located below that region of the insulator 10, inwhich the plane resist layer 20 is virtually completely removed bydeveloping.

[0049] The ratio of the slopes at the upper end of the respective curvedportions of the resist remainders 20 b, 20 c, 20 d can be expressed byα₄>α₃>α₂, i.e. an increasing slope at the upper end of the curvedportion for each resist remainder located further outwards, which passesover in a corresponding increasing slope of the upper end of thestaggered curved portions KB of FIG. 3b.

[0050] For a better illustration of the upper end of the curved portionKB, i.e. the transition area between curved portion and base portion, anenlarged cutout of either FIG. 3a or the outer stage of the field plate1″ of FIG. 3b is illustrated in FIG. 5. FIG. 5 is divided into aleft-hand curved portion KB having a lateral extension b₁ and a baseportion SB having a lateral extension b₂. The substrate 9 is arrangedbelow the insulator profile (consisting of curved portion and baseportion). Right-hand of the base portion begins the outer metalliccoating MET2 having a thickness d_(m), left-hand of the base portion atthe upper end of the curved portion KB begins the inwards curved innermetallic coating MET1, which is applied to a correspondingly curvedsurface OF and having a thickness d_(m). The angle of inclination α atthe upper end of the curved portion is illustrated. It corresponds toangle α₄ or α₁, respectively, with regard to the examples shown in FIG.3a or 3 b. Height h of the base portion SB corresponds to height h₁₀ ofFIGS. 3a, 3 b.

[0051]FIG. 4 together with its enlarged cutout shown in FIG. 4a shows aninsulator profile 11, which may be formed in accordance with the flatinsulator profile of FIG. 3b, which is, however, not comprised of aplurality of staggered arrangements, but comprises a hood 32 extendingabove the insulator profile, which hood serves as a screen and includesan outer curved portion 32 a. It is connected to the anode 31 (above thep+ diffusion area 8) in a voltaically conducting manner and runs atfirst upwards and then laterally outwards with a constant height h₄₁.The region between the lower area of the hood 32 and the insulatorprofile as well as the metallic coating 31, 31 a, 31 b is filled with acasting compound 41, which has an insulating effect. FIG. 4 is not trueto scale, it serves instead to describe the structural elements. Anexemplary, approx. true to scale embodiment of the arrangement accordingto FIG. 4 is shown in FIG. 6.

[0052] It is the purpose of FIG. 4 and the enlarged cutout shown in FIG.4a to describe a detail of the inner end of the curved portion KB of theinsulator profile 11. Said inner end, which substantially begins at theouter end of the p+ diffusion zone 8, is provided in the form of a step11 s, which is formed in an order of magnitude of 20 nm to 30 nm; itmay, however, also deviate from said values, but usually has a height of50 nm, which height is designated “d”. Said step is produced by themethod of production according to FIGS. 2a, 2 b and results from thegraduation of the gray-tone value of the mask during exposure. Thegray-tone value cannot decrease in an infinitely fine manner to zero(permeable mask) so that from a minimum gray-tone value onwards nofurther graduation is effected and step 11 s is at first produced in theresist remainder 20 a or 20 b, respectively, during exposure and is thentransferred into the insulator 10 by dry etching 60. In the region ofstep 11 s, also the course of the metallic coating 31 towards thecontinuously curved portion 31 b, which is free of steps, includes aslight prominence 31 a, which, however, with a metallization thicknessof usually 1 μm, is hardly noticeable compared to the preferred stepheight “d” being within a range of 50 nm and does not cause peak valuesin the course of flux lines.

[0053] A second detail is only schematically visible in FIG. 4, it isthe radius of curvature r=r₃₂ preferably selected here shown as aquarter circle in the curved portion 32 a of the hood 32. It begins atthe distance b₁₀ from the upper end of the curved metallic coating 31 b,which distance is considerably larger than illustrated in FIG. 4 andwhich is shown true to scale in FIG. 6 according to a specific example.In this example, said distance substantially corresponds to the radiusof curvature r within the quarter circle 32 a of the hood 32 above thebase portion SB of the insulator 10.

[0054] Herein the insulator 10, according to FIG. 3b, has a flat heighth₁₀, which is less than 5 μm and is preferably 2 μm. The radius r,illustrated as r₃₂ in FIG. 4, has dimensions of for example 100 μm andthe distance b₁₀, according to FIG. 4, is likewise dimensioned.

[0055] In the example according to FIG. 6, in addition to this also thelateral extension of the curved portion KB of the insulator profile 11is suitably provided with a width b₉, which substantially corresponds tothe width b₁₀. The distance between the bottom surface of the hood 32and the curved field plate 31 b in the curved portion and the baseportion 10, according to the example, is between 10 μm and 30 μm,represented by h₄₁, as shown in FIG. 4. Said region, as well as thecurved portion and the region located laterally further outwards, isfilled with a casting compound 41. It has an insulating effect and formsa mechanical stabilization.

[0056] A semiconductor component capable of blocking is an IGBT, athyristor, a GTO or a diode, especially a Schottky diode. An insulatorprofile (10 a, 10 b, 10 c, 10 d, 11) is provided in the terminationportion of an anode metallic coating (1, 31) and is fixed (directly) onthe substrate (9) of the component and having a curved portion (KB) anda base portion (SB), said insulator profile comprising a surface (OF) inthe curved portion (KB), which begins flat and is curved outwards andupwards in a steadily increasing manner. A metallic coating (MET1; 30 a,30 b, 30 c, 30 d, 31 b) is deposited on the surface (OF), which coatingdirectly follows the surface curvature and laterally extends the inneranode metallic coating. The end of the metallic coating (MET1; 30 a, 30b . . . ) is spaced in an insulating manner by the surrounding baseportion (SB) of the insulator profile (10 a, 11) from an outer metalliccoating (MET2;3) surrounding said base portion.

[0057] A largely constant course of flux lines avoiding peak valuesresults between both metallic coatings (1, 31, MET1; 3, MET2), when oneof a reverse bias voltage and blocking voltage is applied between thespaced metallic coatings.

1. Semiconductor component capable of blocking, such as an IGBT, athyristor, a GTO or a diode, especially a Schottky diode, wherein (a) aninsulator profile (10 a, 10 b, 10 c, 10 d, 11) is provided in atermination portion of an anode metallic coating (1, 31) and is fixed(directly in the termination portion) on a substrate (9) of thecomponent and having a curved portion (KB) and a base portion (SB), saidinsulator profile comprising a surface (OF) in the curved portion (KB),which begins flat and is curved outwards and upwards in a steadilyincreasing manner; (b) a metallic coating (MET1; 30 a, 30 b, 30 c, 30 d,31 b) is deposited on the surface (OF), which coating directly followsthe surface curvature and laterally extends the inner anode metalliccoating; (c) to space an upper end of the curved metallic coating (MET1;30 a, 30 b . . . ) in an insulating manner by the surrounding baseportion (SB) of the insulator profile (10 a, . . . , 11) from an outermetallic coating (MET2;3) surrounding said base portion such that asubstantially constant course of flux lines avoiding peak values resultsbetween both metallic coatings (1, 31, MET1; 3, MET2), when one ofreverse bias voltage and blocking voltage is applied between the spacedmetallic coatings.
 2. Component according to claim 1, wherein aplurality of insulator profiles (10 b, 10 c, 10 d), especially two orthree insulator profiles, each having a curved portion (KB) and baseportion (SB), are arranged in a staggered manner around the inner anodemetallic coating (1), said plurality of insulator profiles being allfixed on the substrate (9), wherein the curved metallic coating (30 b)of the innermost insulator profile conductingly passes over into theanode metallic coating (1) and the surrounding outer metallic coating(3) of the outermost insulator profile (10 d) is provided as a cathodemetallic coating (3) of the component.
 3. Component according to claim2, wherein the steady course of curvature of the curved metalliccoatings (30 b, 30 c, 30 d) is the steeper towards the outside, thefurther outward the associated insulator profile (10 b, 10 c, 10 d) islocated relative to the inner anode metallic coating (1).
 4. Componentaccording to claim 1, wherein only one insulator profile (10 a)surrounds the anode metallic coating (1, 31), said insulator profile (10a) having a height in the base portion (SB), said height being more than5 μm, in particular substantially 10 μm, and the metallic coating (30 a)in the upper portion of the curved portion of the insulator profile isnoticeably inclined (more than 10°), in particular between 15° and 20°,relative to a surface of the substrate (9), and a lateral distance of anupper end of the curved portion (KB) from an inner end of the outermetallic coating (3) is not less than, in particular substantially, tentimes the height of the base portion (SB) of the insulator profile (10a).
 5. Component according to claim 1, wherein only one insulatorprofile (10 a) surrounds the anode metallic coating (1, 31), saidinsulator profile (11) being flat in the base portion (SB) and having aheight of less than 5 μm, in particular substantially 2 μm, and an upperportion of the metallic coating (31 b) is slightly curved, especiallyinclined by a maximum of approx. 10° relative to the surface of thesubstrate (9), wherein a distance of said upper end of the only slightlycurved metallic coating (31 b) from an inner end of the outer metalliccoating (3) is more than ten times the height of the base portion (SB),in particular more than fifty times to two-hundred times the height ofthe base portion (SB), wherein the anode (31) extends along a curvedhood (32, 32 a) running particularly analogously to the curved portionin a continued manner in a distance (h₄₁) above the insulator profile(11), and an insulating mass (41) is provided between the insulatorprofile (11) and the hood (32).
 6. Semiconductor component capable ofblocking according to any one of the previous claims for powerelectronics; or method for producing a termination portion of saidcomponent, wherein the insulator profile (10 a, 10 b) including saidcurved surface (OF), which is free of steps, is produced or may beproduced by gray-tone lithography in the termination portion of an anode(1; 31), wherein (a) the substrate (9) is covered with an insulatinglayer (10) having a thickness of in particular between 0.5 μm and 15 μm;(b) said insulator layer having a thickness is covered with aphotosensitive layer (photoresist layer; 20); (c) the photoresist layer(20) is exposed through a mask, which changes in its gray-tone value inaccordance with the course of curvature of the surface (OF) of at leastone insulator profile (10 a, 10 b, 10 c, 10 d), and is subsequentlystructured to form at least one resist remainder (20 a, 20 b, 20 c, 20d); (d) the structured photoresist layer (20 a, 20 b, 20 c, 20 d) andthe insulator layer (10) are substantially planely removed by adry-etching process, in order to transfer the at least one resistremainder—defined by the structuring—by shape into the insulator (10)and to form (10 a, 10 b, 10 c, 10 d) at least one insulator profilearound the anode (1; 31).
 7. Component according to claim 5, wherein thecurvature (32 a, r) of the hood (32), extending particularly as aquarter circle, is greater or more pronounced than the curvature of thelaterally extended metallic coating (31 b).
 8. Component according toany one of claims 1 to 4, wherein a transition (31 a) of the curvedmetallic coating (31 b) to the anode metallic coating (31) is providedthrough a small step (d) of the insulator profile at an inner end of thecurved portion (KB) of the insulator profile (11), wherein said smallstep is in an order of magnitude of 5 nm to 30 nm so that the insulatorprofile does not terminate towards the anode metallic coating (31)completely free of steps.
 9. Component or method according to any one ofthe previous claims, wherein—after metallizing the curved surface (OF)of the insulator profile (10 a)—a wall-like casting compound (40) isdeposited around the one or at least one of the plurality of insulatorprofiles (10 c), which casting compound insulatingly overlaps themetallic coatings (MET1, MET2) on both ends of the insulator profile (10a).
 10. Component according to claim 2 or 3, wherein below each of theplurality of insulator profiles (10 c, 10 d), which are arranged in anoutwards staggered manner, a strip-shaped—ring-strip shaped for acircular anode (1)—compensating area is diffused into the substrate (9)as a zone (7 a, 7 b) in order to transfer the potential present at thecomponent at the respective location when a voltage is applied from thesubstrate area to the respective metallic coating (30 c, 30 d) of therespective insulator profile (10 c, 10 d), wherein the width of thestrip is smaller than the width of the respective associated insulatorprofile and at least sliqhtly overlaps the end of the insulator profile(10 b) located further inwards.
 11. Component or method according toclaim 6, wherein the curved surface of the at least one insulatorprofile is metallized (31), wherein the structuring according to feature(c) is effected prior thereto by developing the exposed photoresistlayer (20) and is transferred into the insulator layer (10) according tofeature (d).
 12. Component according to any one of the previous claims,comprising a substrate (9) made of silicon carbide (SiC), which has avery low diffusion constant for doting substances.
 13. Componentaccording to claim 5, wherein an intermediate region (b₁₀) is formedbetween the curved portion of the hood (32 a) and the laterallyextended, curved metallic coating (31 b), in which intermediate regionthe hood (32) has a substantially constant distance from the baseportion (11, SB).
 14. Component according to claim 5 or 13, wherein thebase portion (SB) also extends below the curved hood portion (32 a).